The invention relates to a process and an apparatus for heating and melting lumps of sponge ion.
In a known process of the specified kind, metallic iron carriers are heated in a charging material preheater arranged above a melting furnace, and then fed to the furnace. In that case, an economical mode of operation is only possible if the iron carriers used are materials which do not involve excessive reactivity in relation to oxygen, as it is only then that the energy content of the waste gases from the melting furnace can be economically used for the preheating effect, by virtue of post-combustion of the waste gases. If directly reduced material in lump form, that is to say sponge iron in lump form, is to be preheated, then its high level of reactivity, in particular at temperatures above 500.degree. C., requires a reducing atmosphere in order to prevent major oxidation losses when the sponge iron is heated. For that purpose, the sponge iron has been heated, mixed with coke, in a preheater. However such a process necessitates a considerable surplus of energy-rich waste gases and presupposes gas consumers in the vicinity of the installation.
The invention is based on the problem of permitting preheating of the highly reactive sponge iron to temperatures of about 850.degree. C. without substantial oxidation losses, and at the same time avoiding a surplus of energy-rich waste gases. The invention also seeks to provide an apparatus for carrying out that process.